In the present thesis, the influence of different prevention techniques on the bloodserum-calcium-concentration post-partum was tested on a dairy farm with 1950 Holstein-Friesian-Cows in milk. The objective was to find ways for further reducing the incidence of parturient paresis and subclinical hypocalcemia in the future in addition to the working feeding of anionic salts in the dry period. For this purpose, blood was taken every two hours from 291 cows, including ten heifers, in the first 24 hours post-partum and the serum-calcium-concentration was determined. The cows were separated into three large groups: Different lactation numbers, different administrations of calcium or variation in the frequency of milk withdrawal and oral administration of a drench with calcium.

The lactation number showed a significant influence, whereas the serum-calcium-concentration declined with increasing age. The oral administration of a calcium bolus is not necessary for animals of the first and second lactation. An effect could not statistically be proven for cows of the third and older lactations. The infusion of calciumborogluconate turned out to be the only administration of calcium that could elevate the mean serum-calcium-concentration into the physiological range for a longer period of time. The administration of a bolus as well as dosing of a calcium containing drench did not show a statistically provable increase of the serum-calcium-concentration compared to cows that had not been given calcium. The variation in the amount and frequency of milk withdrawal post-partum did not result in any differences between the groups and therefore cannot be recommended. A statistically proven decline in the serum-calcium-concentration of 0,05 mmol/l caused by milk withdrawal could be shown after the third milking post-partum. More precise predications require further investigations with blood samples being taken several minutes before and after milk withdrawal.

The intramuscular injection of 15 million IU Vitamin D3 seven days before the estimated calving date showed a highly significant influence on cows of the fifth and older lactations. The injection resulted in serum-calcium-concentrations which were on average in the physiological range for 24 hours post-partum whereas the cows without an administration of Vitamin D3 were hypocalcemic. The combination of feeding anionic salts in the late dry perioid and the injection of Vitamin D3 should be further investigated regarding the point in time of the injection, dosing and side effects.
Feeding anionic salts in the late dry period proved to be very effective. Whether and if the incidence of parturient paresis currently still can be reduced should be verified in further investigations.